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Outline processes of external respiration and specify driving pressure and physical mechanism responsible for each process

1. Ventilation: between atmosphere and the alveoli in the lungs
2. Gas exhange of co2 and o2 in alveoli and blood of pulmonary capillaries
3. Transport of co2 and o2 in the blood between lungs and tissues
4. exhange of o2 and co2 between cells in capillaries and tissue cells.

All driven by Pressure gradients.
- Bulk Flow: large distances (air pressure gradient-for ventilation and breathing and blood pressure gradient-for blood gas transport)
-Diffusion: short distances: gas exchange driven by partial pressures of individual gases (co2 and o2


Describe role of upper airways in function, air conditioning, airway patency, and OSA

Upper airways have common functions: breathing, digestion, phonation (speaking)
-3 things close during swallowing
1. uvula inhibits food coming back up
2. epiglottis directs food to esophagus not trachea
3. vocal chords allow speaking and prevent food getting into lungs

Air conditioning: by upper airway mucosal lining
-Inspiration: mucosal lining loses heat and moisture to heat the air (make it saturated and warm)
-Expiration: partial recovery of heat and moisture, remaining leftovers come from blood supply.
---blood flow is very important here.

Airway Patency: 20 muscles control them, keeps them open.
- Inspiration can create a negative pressure (less than atmospheric) and cause collapse.

OSA: sleep apnea happens when the tone of muscles is less than normal, will relax muscles and tongue goes into upper airway and makes air hard to get in.


Outline functional differences between conducting and the respiratory zones of tracheobronchial tree.

Conducting zone: provides a pathway for bulk flow, requires energy, muscles alter volume to change pressure relative to the atmosphere to drive movement inwards.
Respiratory zone: alveoli where gas exchange actually takes place. (diffusion via partial pressure differences)


Describe functional significance of alveolar cell types and structural layers of the alveolar-capillary membrane

Designed for gas exchange. 600 million in the lungs with hundreds of pulmonary capillaries.

Type1: Pneumocyte:
- flat squamous epithilium (fried egg w nucleus)
- 95% alveolar surface area
- thin (0.1-0.3 microns)
- total surface area is half a tennis court (100m2)
-largest surface area

Type2: Granular Pneumocyte/Septal cell
- cuboidal shape (boxy)
- contain lamellar inclusion bodies that store PULMONARY SURFACTANT
- this is a mix of lipids and proteins that reduce alveolar surface tension (mostly lipids)
-diphosphatidycholine (DPPC) is reducing ST agent

Type3: Alveolar Macrophage/ Dust Cell
- this bad boy sits on the extracellular lining and eats bad things. (phagocytosis and migratory-walks around)

Air-blood barrier is very thin.
you have air, surfactant, alveolar epithelium, interstitium, capillary endothelium and blood plasma.

- mechanically structural component to join the two. Contains collagen and elastin that affect compliance. (allowing airways to expand and spring back)
- Provide space for drainage in the lymphatic system.


Describe airway clearance mechanisms and outline examples of mucociliary transport impairment

Big particles >10um: filtered by nasal hairs, irritant receptors that make you sneeze.

Medium particles 2-10um: mucociliary clearance system lining airways before the terminal bronchioles, irritant receptors that make you cough

Smaller particles <2um: macrophage (type 3 cells) that eats it up with a toxin. If this doesn't work then the toxin is spilled and macophage is destroyed and this causes ISSUES.

MCC Transport is mucous and cilia. Cilia are under a 2 layered mucous blanket (1 layer is GEL: sticky and viscous, 2nd layer is SOL: aqueous (PCL) and lower viscocity. allow cilia "beating stroke").
Cells move in a wave (12-15HZ) back up to the mouth through vocal chords so that you can swallow the bad stuff.

If it doesn't work properly, like in
1. smoking (increase mucous production, very viscous, reduces other stuff like ciliary length, number, motility)
2. pathogenic microbes (paralyze ciliary motion)
3. ciliary dyskinesia (inherited, reduce ciliary motility)
4. cystic fibrosis. (increase mucous viscosity, harder to transport bad stuff, genetic issue)

reduced airway clearance and increased chest infection.


Describe the role of alveolar macrophage in airway clearance and in lung scarring (pulmonary fibrosis).

Some sharp particles damage the phagocytic cell (macrophage) and cause the epithelium injury resulting in inflammation, scar formation, collagen deposition, pulmonary fibrosis.
(asbestos, silica dust etc.)


What is the role of cartilage? Which type of cells have it?

Trachea has C shaped cartilage to resist collapse.
Bronchi however have interspersed with smooth muscle
Bronchioles have mostly smooth with no cartilage
- terminal bronchioles only conducting function
- respiratory bronchioles allow gas exchange
- alveolar ducts terminate in alveolar sacs


Describe changes in airway wall.

Decrease in epithelial height, loss cartilage, smooth muscles, and mucous glands as you go down the generations.